mei: stop the stall timer worker if not needed

The stall timer worker checks periodically if there is a stalled i/o
transaction. The issue with the current implementation is that the timer
is ticking also when there is no pending i/o transaction.
This patch provides a simple change that prevents rescheduling
of the delayed work when there is no pending i/o.

Cc: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/mei/amthif.c

@@ -277,6 +277,7 @@ void mei_amthif_complete(struct mei_cl *cl, struct mei_cl_cb *cb)
 	case MEI_FOP_WRITE:
 		if (!cb->status) {
 			dev->iamthif_stall_timer = MEI_IAMTHIF_STALL_TIMER;
+			mei_schedule_stall_timer(dev);
 			mei_io_cb_free(cb);
 			return;
 		}